I believe that PDF and Flash will hang around for quite some time. They are too widespread to disappear quickly. But I am excited about the rise of HTML5 and the gradual replacement of these closed formats. For instance, Scribd’s move to HTML5 is one such step. The reason for my excitement is mostly because I don’t like how PDF and Flash often break basic ingredients of the web, such as linking and search (yes, I am aware that there are workarounds, but they are ugly).